Mapping of rfa Genes in Salmonella typhimurium by ES18 and P22 Transduction and by Conjugation

Abstract

Loci termed rfa , determining biosynthesis of somatic lipopolysaccharide core, have been mapped in Salmonella typhimurium LT2. The smooth-specific phage P22 co-transduced two leaky rfa alleles with cysE and with pyrE ; one of the leaky alleles is perhaps rfaG , and the other is an unidentified gene concerned with synthesis of the heptose-containing part of the core. The lipopolysaccharide-indifferent phage ES18 (or its variant ES18. h1 ) co-transduced rfaF, rfaG, rfaL, rfa (R-res-1), and rfa (R-res-2) alleles with cysE and with pyrE , at rates indicating the order cysE–rfaF –( rfa [R-res-1], rfa [ r-res-2 ], rfaL )– rfaG–pyrE . One proven (and two suspected) rfaE alleles and five proven rfaH alleles were not co-transduced with cysE or pyrE . Hfr crosses indicated that the proven rfaE allele mapped between serA and strA .